The Wisdom of Crowds has been touted as panacea for the prediction markets. The criticisms, though, of late are coming fast and furious. WSJ gets on the wagon:
The problem with these markets, Mr. Plott says, isn't that they are thinly traded, a common complaint, but that they are often plagued by bad information. That leads to bubbles, head-fakes and manipulation -- just like in the stock markets.
The people who bought Rudy Giuliani presidential futures had no better insight than the people who bought Yahoo at $100 a share.
I happen to agree. I think the bulk of these markets, just like any market, are driven by misinformed and under-informed traders that parse the same information from the same news sources. So, you have people trading on information from the media that has been proven wrong time and again.